CO Effect on the Dynamics of Platinum Nucleation/Growth Under the Liquid-Phase Synthesis of Pt/C Electrocatalysts

Abstract

This paper shows how bubbling the reaction medium with CO affects the nucleation/growth of Pt nanoparticles under the synthesis using formic acid or formaldehyde as reducing agents. CO has been found to affect not only the dynamics of the Pt(IV) to Pt x 0 transformation but also the size of the formed particles (1.1–3.9 nm) deposited on the carbon support (ca. 20 wt% Pt). The dual role of CO due to combining the functions of a stabilizer and a reducing agent has been shown. The study demonstrates that the introduction of the dispersed carbon support to the reaction medium leads to the enhancement of the CO positive effect on the microstructure of Pt/C catalysts. In this case, the spatial distribution of Pt nanoparticles over the carbon support surface becomes more uniform that is conducive to increasing the electrochemical surface area. Thus, CO is a unique reagent used to control the microstructure of Pt nanoparticles during their wet synthesis.